System for additive manufacturing

ABSTRACT

A system is disclosed for additive manufacturing of a composite structure. The system may include an outlet through which a composite material is discharged, and a nose that is a component separate from the outlet and located at a distal end of the outlet. The nose may be biased axially relative to the outlet, from a retracted position to an extended position. The nose extends axially past the distal end of the outlet in the extended position.

RELATED APPLICATIONS

This application is based on and claims the benefit of priority fromU.S. Provisional Application No. 62/769,498 that was filed on Nov. 19,2018, the contents of which are expressly incorporated herein byreference.

TECHNICAL FIELD

The present disclosure relates generally to a manufacturing system and,more particularly, to a system for manufacturing system.

BACKGROUND

Extrusion manufacturing is a known process for producing continuousstructures. During extrusion manufacturing, a liquid matrix (e.g., athermoset resin or a heated thermoplastic) is pushed through a diehaving a desired cross-sectional shape and size. The material, uponexiting the die, cures and hardens into a final form. In someapplications, UV light and/or ultrasonic vibrations are used to speedthe cure of the liquid matrix as it exits the die. The structuresproduced by the extrusion manufacturing process can have any continuouslength, with a straight or curved profile, a consistent cross-sectionalshape, and excellent surface finish. Although extrusion manufacturingcan be an efficient way to continuously manufacture structures, theresulting structures may lack the strength required for someapplications.

Pultrusion manufacturing is a known process for producing high-strengthstructures. During pultrusion manufacturing, individual fiber strands,braids of strands, and/or woven fabrics are coated with or otherwiseimpregnated with a liquid matrix (e.g., a thermoset resin or a heatedthermoplastic) and pulled through a stationary die where the liquidmatrix cures and hardens into a final form. As with extrusionmanufacturing, UV light and/or ultrasonic vibrations are used in somepultrusion applications to speed the cure of the liquid matrix as itexits the die. The structures produced by the pultrusion manufacturingprocess have many of the same attributes of extruded structures, as wellas increased strength due to the integrated fibers. Although pultrusionmanufacturing can be an efficient way to continuously manufacturehigh-strength structures, the resulting structures may lack the form(shape, size, and/or precision) required for some applications. Inaddition, during conventional multi-fiber pultrusion, ensuring adequatewetting and bonding between adjacent fibers can be problematic.

The disclosed system is directed to addressing one or more of theproblems set forth above and/or other problems of the prior art.

SUMMARY

In one aspect, the present disclosure is directed to a system foradditive manufacturing. The system may include an outlet through which acomposite material is discharged, and a nose that is a componentseparate from the outlet and located at a distal end of the outlet. Thenose may be biased axially relative to the outlet, from a retractedposition to an extended position. The nose extends axially past thedistal end of the outlet in the extended position.

In another aspect, the present disclosure is directed to another systemfor additive manufacturing. The system may include an outlet throughwhich a composite material is discharged, and a nose that is a componentseparate from the outlet and located at a distal end of the outlet. Amaterial forming the outlet may be harder than a material forming thenose. The nose may extend axially past the distal end of the outlet.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric illustration of an exemplary disclosed additivemanufacturing system; and

FIGS. 2, 3, 4, and 5 are cross-sectional illustrations of exemplarydisclosed print heads that may be utilized with the additivemanufacturing system of FIG. 1.

DETAILED DESCRIPTION

FIG. 1 illustrates an exemplary system 10, which may be used tomanufacture a composite structure 12 having any desired cross-sectionalshape (e.g., ellipsoidal, polygonal, etc.). System 10 may include atleast a moveable support 14 and a print head (“head”) 16. Support 14 maybe coupled to and configured to move head 16. In the disclosedembodiment of FIG. 1, support 14 is a robotic arm capable of moving head16 in multiple directions during fabrication of structure 12, such thata resulting longitudinal axis of structure 12 is three-dimensional. Itis contemplated, however, that support 14 could alternatively be agantry, a hybrid gantry/arm, or another type of movement system that iscapable of moving head 16 in multiple directions during fabrication ofstructure 12. Although support 14 is shown as being capable ofmulti-axis movement (e.g., movement about six or more axes), it iscontemplated that any other type of support 14 capable of moving head 16in the same or in a different manner could also be utilized, if desired.In some embodiments, a drive may mechanically couple head 16 to support14 and may include components that cooperate to move and/or supply poweror materials to head 16.

Head 16 may be configured to receive or otherwise contain a matrix. Thematrix may include any type of material (e.g., a liquid resin, such as azero-volatile organic compound resin; a powdered metal; a solidfilament; etc.) that is curable. Exemplary matrixes include thermosets,single- or multi-part epoxy resins, polyester resins, cationic epoxies,acrylated epoxies, urethanes, esters, thermoplastics, photopolymers,polyepoxides, thiols, alkenes, thiol-enes, reversible resins (e.g.,Triazolinedione, a covalent-adaptable network, a spatioselectivereversible resin, etc.) and more. In one embodiment, the matrix insidehead 16 may be pressurized, for example by an external device (e.g., anextruder or another type of pump—not shown) that is fluidly connected tohead 16 via a corresponding conduit (not shown). In another embodiment,however, the matrix pressure may be generated completely inside of head16 by a similar type of device. In yet other embodiments, the matrix maybe gravity-fed through and/or mixed within head 16. In some instances,the matrix inside head 16 may need to be kept cool and/or dark toinhibit premature curing; while in other instances, the matrix may needto be kept warm for similar reasons. In either situation, head 16 may bespecially configured (e.g., insulated, temperature-controlled, shielded,etc.) to provide for these needs.

The matrix may be used to coat, encase, or otherwise at least partiallysurround or saturate (e.g., wet) any number of continuous reinforcements(e.g., separate fibers, tows, rovings, ribbons, and/or sheets ofmaterial) and, together with the reinforcements, make up at least aportion (e.g., a wall) of composite structure 12. The reinforcements maybe stored within (e.g., on separate internal spools) or otherwise passedthrough head 16 (e.g., fed from one or more external spools). Whenmultiple reinforcements are simultaneously used, the reinforcements maybe of the same type and have the same diameter and cross-sectional shape(e.g., circular, square, flat, hollow, solid, etc.), or of a differenttype with different diameters and/or cross-sectional shapes. Thereinforcements may include, for example, carbon fibers, vegetablefibers, wood fibers, mineral fibers, glass fibers, metallic wires,optical tubes, etc. It should be noted that the term “reinforcement” ismeant to encompass both structural and non-structural types ofcontinuous materials that can be at least partially encased in thematrix discharging from head 16.

The reinforcements may be exposed to (e.g., at least partially coated orimpregnated with) the matrix while the reinforcements are inside head16, while the reinforcements are being passed to head 16 (e.g., as aprepreg material), and/or while the reinforcements are discharging fromhead 16, as desired. The matrix, dry reinforcements, and/orreinforcements that are already exposed to the matrix (e.g., wettedreinforcements) may be transported into head 16 in any manner apparentto one skilled in the art.

The matrix and reinforcement may be discharged from head 16 via at leasttwo different modes of operation. In a first mode of operation, thematrix and reinforcement are extruded (e.g., pushed under pressureand/or mechanical force) from head 16, as head 16 is moved by support 14to create the 3-dimensional shape of structure 12. In a second mode ofoperation, at least the reinforcement is pulled from head 16, such thata tensile stress is created in the reinforcement during discharge. Inthis mode of operation, the matrix may cling to the reinforcement andthereby also be pulled from head 16 along with the reinforcement, and/orthe matrix may be discharged from head 16 under pressure along with thepulled reinforcement. In the second mode of operation, where the matrixmaterial is being pulled from head 16 with the reinforcement, theresulting tension in the reinforcement may increase a strength ofstructure 12 (e.g., by aligning the reinforcements, inhibiting buckling,equally distributing loads, etc.), while also allowing for a greaterlength of unsupported structure 12 to have a straighter trajectory(e.g., by creating moments that oppose gravity).

The reinforcement may be pulled from head 16 as a result of head 16moving away from an anchor point 18. In particular, at the start ofstructure-formation, a length of matrix-impregnated reinforcement may bepulled and/or pushed from head 16, deposited onto a stationary ormoveable anchor point 18, and cured, such that the discharged materialadheres to anchor point 18. Thereafter, head 16 may be moved away fromanchor point 18, and the relative movement may cause additionalreinforcement to be pulled from head 16. It should be noted that themovement of the reinforcement through head 16 could be assisted (e.g.,via internal feed mechanisms), if desired. However, the discharge rateof the reinforcement from head 16 may primarily be the result ofrelative movement between head 16 and anchor point 18, such that tensionis created within the reinforcement.

Any number of reinforcements may be passed axially through head 16 andbe discharged together with at least a partial coating of matrix. Atdischarge (or shortly thereafter), one or more cure enhancers (e.g., oneor more light sources, ultrasonic emitters, lasers, heaters, catalystdispensers, microwave generators, etc.) 20 may expose the matrix coatingto a cure energy (e.g., light energy, electromagnetic radiation,vibrations, heat, a chemical catalyst or hardener, or other form ofactively-applied energy). The cure energy may trigger a chemicalreaction, increase a rate of chemical reaction already occurring withinthe matrix, sinter the material, harden the material, or otherwise causethe material to cure as it discharges from head 16.

A controller 22 may be provided and communicatively coupled with support14, head 16, and/or any number and type of cure enhancers 20. Controller22 may embody a single processor or multiple processors that include ameans for controlling an operation of system 10. Controller 22 mayinclude one or more general- or special-purpose processors ormicroprocessors. Controller 22 may further include or be associated witha memory for storing data such as, for example, design limits,performance characteristics, operational instructions, matrixcharacteristics, reinforcement characteristics, characteristics ofstructure 12, and corresponding parameters of each component of system10. Various other known circuits may be associated with controller 22,including power supply circuitry, signal-conditioning circuitry,solenoid/motor driver circuitry, communication circuitry, and otherappropriate circuitry. Moreover, controller 22 may be capable ofcommunicating with other components of system 10 via wired and/orwireless transmission.

One or more maps may be stored in the memory of controller 22 and usedduring fabrication of structure 12. Each of these maps may include acollection of data in the form of models, lookup tables, graphs, and/orequations. In the disclosed embodiment, the maps are used by controller22 to determine desired characteristics of cure enhancers 20, theassociated matrix, and/or the associated reinforcements at differentlocations within structure 12. The characteristics may include, amongothers, a type, quantity, and/or configuration of reinforcement and/ormatrix to be discharged at a particular location within structure 12,and/or an amount, intensity, shape, and/or location of desired curing.Controller 22 may then correlate operation of support 14 (e.g., thelocation and/or orientation of head 16) and/or the discharge of materialfrom head 16 (a type of material, desired performance of the material,cross-linking requirements of the material, a discharge rate, etc.) withthe operation of cure enhancers 20, such that structure 12 is producedin a desired manner.

Head 16 may be an assembly of multiple components that cooperate todischarge matrix-coated reinforcements. These components may include,among other things, a matrix reservoir 24 and an outlet (e.g., a nozzle)26. Matrix reservoir 24 may be configured to hold a finite supply ofmatrix material sufficient to wet a desired length of reinforcementspassing therethrough. In some embodiments, matrix reservoir 24 may beautomatically replenished with matrix (e.g., based on a sensed amount ofmatrix remaining in reservoir 24). Outlet 26 may be located at adischarge end of matrix reservoir 24 and configured to receive thematrix-coated reinforcements therefrom. Cure enhancer(s) 20 may bemounted at the discharge end of matrix reservoir 24 and adjacent (e.g.,at a trailing edge of and/or around) outlet 26.

An exemplary head 16 is disclosed in detail in FIGS. 2 and 3. As shownin these figures, outlet 26 of head 16 may include unique features thatare configured to improve a quality of the material discharging fromhead 16. In particular, in some situations, it may be possible for thematrix-coated reinforcements to include voids (e.g., air bubbles),ridges, frayed ends, or other irregularities that inhibit adhesionbetween fibers or create uneven and rough surface textures. In thesesituations, compressing (e.g., pressing the material into an adjacentlayer) the discharged material prior to and/or during curing may improvethe quality of structure 12. For this purpose, a nose 30 may beslidingly located around outlet 26. Nose 30 may be configured to slidein an axial direction of outlet 26 between a retracted (i.e.,non-compacting) position located closest to matrix reservoir 24 andextended (i.e., compacting) position located furthest from matrixreservoir 24. As shown in FIG. 2, nose 30 may extend axially past aterminal end of outlet 26 when at the extended location. As shown inFIG. 3, an outer end surface of nose 30 may be generally flush (e.g.,within engineering tolerances) with the terminal end of outlet 26 duringcompacting of the matrix-coated reinforcements.

Nose 30 may be biased toward the extended position (e.g., via one ormore springs 32). With this arrangement, nose 30 may ride over and exerta flattening or compacting force on the material discharging throughoutlet 26, just prior to the material being exposed to cure energy fromcure enhancer(s) 20. The compressing force may function to press out airbubbles, improve resin impregnation, consolidate loose fibers, andotherwise smooth surface features.

In the embodiment of FIGS. 2 and 3, nose 30 is ring-like (e.g.,annularly surrounding outlet 26) and flat at the outer end surface. Aradial outer edge at the end surface may be rounded or chamfered, toreduce a likelihood of catching on, cutting, or otherwise damagingstructure 12. Similarly, a radial inner edge at the end surface may alsobe rounded or chamfered to inhibit catching, cutting, or breaking of thecontinuous reinforcement passing therethrough, if desired. In theseembodiments, nose 30 may have a complimentary shape (e.g., a continuingradius or chamfer), if desired.

A material that forms nose 30 may be relatively softer than a materialforming outlet 26 (e.g., at least the nozzle tip), such that nose 30 maywear away faster than outlet 26. For example, the outlet material may beharder than the nose material by at least 10%, when using conventionalhardness scales known in the art (e.g., when using the Brinell HardnessScale, the Rockwell Hardness Scale, the Knoop Hardness Scale, theVickers Hardness Scale, etc.). In one example, outlet 26 may befabricated from stainless steel or aluminum, while nose 30 may befabricated from rubber, plastic, or other polymer. In this arrangement,nose 30 may function as a replaceable sacrificial layer that protectsoutlet 26 from excessive wear.

While nose 30 may have a generally square cross-sectional shape in theembodiments of FIGS. 2 and 3, nose 30 could have other shapes, ifdesired. For example, FIG. 4 illustrates nose 30 as being conical orfrustoconical, with a smaller axial end surface.

Over a period of use, nose 30 may wear away and no longer have a shapeand/or texture required for efficiently engaging the materialdischarging through outlet 26. When this occurs, head 16 may bemaneuvered (e.g., via support 14) over the top of a resurfacer 34 thatis configured to restore an outer profile of nose 30 to a near-originalshape, size, and/or texture. In the embodiment of FIG. 4, resurfacer 34resembles a sharpener having one or more blades 36 that are positionedand/or oriented at precise locations for the particular configuration ofnose 30. In other embodiments, however, resurfacer 34 could embody asander, a hot iron, a mold, or another similar device.

It is contemplated that nose 30 may be coated with a substance thatinhibits the matrix material from sticking to nose 30 during thecompacting operation described above. For example, nose 30 may be coatedwith a release wax, petroleum jelly, a PTFE coating, etc. In thissituation, resurfacer 34 may be further capable of reapplying thatcoating. For example, resurfacer 34 may include a spray jet, an orifice,or another mechanism (not shown) that advances the coating onto nose 30when nose 30 is brought near and/or into contact with resurfacer 34.Resurfacer 34 may be mounted on or adjacent support 14 (referring toFIG. 1), for example connected to a build chamber floor, wall, or othersimilar structure.

FIG. 5 illustrates another embodiment of print head 16 that may be usedin conjunction with system 10. In this embodiment, nose 30 does notannularly surround outlet 26. In contrast, nose 30 may be connected atan axial end of outlet 26 such that nose 30 functions as an extension ofoutlet 26. In this embodiment, since nose 30 may always protrude pastoutlet 26, springs 32 may be omitted. Resilience of nose 30, in thisembodiment, may primarily be associated with the material of nose 30.For example, nose 30 may be fabricated from an elastomeric material. Itshould be noted, however, that an axial distance between the extended(i.e., non-compacting) and retracted (i.e., compacting) positions may beless for this embodiment.

INDUSTRIAL APPLICABILITY

The disclosed systems may be used to continuously manufacture compositestructures having any desired cross-sectional size, shape, length,density, and/or strength. The composite structures may include anynumber of different reinforcements of the same or different types,diameters, shapes, configurations, and consists, each coated with acommon matrix material. In addition, the disclosed heads may allow forcompaction and/or smoothing of structural surfaces and, thereby, anincreased strength and/or performance. Operation of system 10 will nowbe described in detail.

At a start of a manufacturing event, information regarding a desiredstructure 12 may be loaded into system 10 (e.g., into controller 22 thatis responsible for regulating operations of support 14 and/or head 16).This information may include, among other things, a size (e.g.,diameter, wall thickness, length, etc.), a contour (e.g., a trajectory),surface features (e.g., ridge size, location, thickness, length; flangesize, location, thickness, length; etc.), connection geometry (e.g.,locations and sizes of couplings, tees, splices, etc.), desired weavepatterns, weave transition locations, location-specific matrixstipulations, location-specific reinforcement stipulations, densitystipulations, etc. It should be noted that this information mayalternatively or additionally be loaded into system 10 at differenttimes and/or continuously during the manufacturing event, if desired.Based on the component information, one or more different reinforcementsand/or matrix materials may be selectively installed and/or continuouslysupplied into system 10.

Installation of the reinforcements may be performed by passing thereinforcements down through matrix reservoir 24, and then threading thereinforcements through outlet 26 and nose 30. Installation of the matrixmaterial may include filling head 16 and/or coupling of an extruder (notshown) to head 16.

Head 16 may then be moved by support 14 under the regulation ofcontroller 22 to cause matrix-coated reinforcements to be placed againstor on a corresponding anchor point 18. Cure enhancers 20 may then beselectively activated to cause hardening of the matrix materialsurrounding the reinforcements, thereby bonding the reinforcements toanchor point 18.

The component information may then be used to control operation ofsystems 10 and 12. For example, the reinforcements may be pulled and/orpushed from head 16 (along with the matrix material), while support 14selectively moves head 16 in a desired manner during curing, such thatan axis of the resulting structure 12 follows a desired trajectory(e.g., a free-space, unsupported, 3-D trajectory). As the separatereinforcements are pulled through head 16, the reinforcements may passunder nose 30 and be flattened and/or compressed into a desiredthickness and/or contour. Once structure 12 has grown to a desiredlength, structure 12 may be disconnected (e.g., severed) from head 16 inany desired manner.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the disclosed systems andhead. Other embodiments will be apparent to those skilled in the artfrom consideration of the specification and practice of the disclosedsystems and heads. It is intended that the specification and examples beconsidered as exemplary only, with a true scope being indicated by thefollowing claims and their equivalents.

What is claimed is:
 1. A system for additively manufacturing,comprising: an outlet through which a composite material is discharged;and a nose that is a component separate from the outlet and located at adistal end of the outlet, wherein: the nose is biased axially relativeto the outlet, from a retracted position to an extended position; andthe nose extends axially past the distal end of the outlet in theextended position.
 2. The system of claim 1, further including at leastone spring configured to bias the nose axially relative to the outlet.3. The system of claim 1, further including a matrix reservoir locatedat a side of the outlet opposite the nose, the matrix reservoirconfigured to wet a continuous reinforcement with a matrix to form thecomposite material.
 4. The system of claim 3, further including a cureenhancer configured to expose the matrix in the composite material to acure energy after the nose has passed over the composite material. 5.The system of claim 4, further including a support configured to movethe matrix reservoir, the outlet, and nose together.
 6. The system ofclaim 5, further including a controller in communication with the cureenhancer and the support, the controller being configured to coordinateoperations of the support and the cure enhancer based on specificationsfor a structure to be manufactured from the composite material.
 7. Thesystem of claim 5, wherein the support is located at a side of thematrix reservoir opposite the outlet.
 8. The system of claim 1, whereinthe nose annularly surrounds the distal end of the outlet.
 9. The systemof claim 1, wherein the nose extends axially from the distal end of theoutlet.
 10. The system of claim 1, further including a coating on anouter end surface of the nose, the coating configured to inhibit thecomposite material from sticking to the nose.
 11. The system of claim 1,wherein a material forming the outlet is harder than a material formingthe nose.
 12. The system of claim 11, wherein: the material forming theoutlet is one of stainless steel or aluminum; and the material formingthe nose is a polymer.
 13. The system of claim 1, wherein duringoperation, an end surface of the nose is generally flush with an endsurface of the outlet.
 14. The system of claim 1, further including aresurfacer configured to restore an outer profile of the nose.
 15. Thesystem of claim 1, wherein the nose is biased via a materialcharacteristic of the nose.
 16. The system of claim 15, wherein the noseis fabricated from an elastomeric material.
 17. The system of claim 1,wherein an outer radial edge at an axial end surface of the nose is atleast one of rounded and chamfered.
 18. The system of claim 1, whereinan inner radial edge at an axial end surface of the nose is at least oneof rounded and chamfered.
 19. The system of claim 18, wherein an innerradial edge of the outlet at the distal end has a shape complimentary tothe inner radial edge at the axial end surface of the nose.
 20. A systemfor additively manufacturing, comprising: an outlet through which acomposite material is discharged; and a nose that is a componentseparate from the outlet and located at a distal end of the outlet,wherein: a material forming the outlet is harder than a material formingthe nose; and the nose extends axially past the distal end of theoutlet.